Method of forming continuously-cast metal strand into integral billets



,1969 E. SCHNECKENBURGER Erm- 3,483,915

METHOD OF FORMING GQNTINUOUSLY'CAST METAL STRAND INTO INTEGRAL BILLETS'Oidginal Filed June 17, 1964 9 Sheets-Sheet 1 m ME . Q 53 QR mm .E 1 kmm .mN MN NW m 2c L:

Dec. I6, 1969 METHOD OF FORMING CONTINUOUSLY-CAST METAL STRAND OriginalFiled June 17, 1964 (.g Q unmmllim ill E. SCHNECKENBURGER ET AL INTOINTEGRAL BILLETS 9 Sheets-Sheet 2 llill Dec. 1939 E. SCHNECKENBURGERETAL. 3,483,915

METHOD OF FORMING CQNTINUOUSLY'CAST METAL STRAND INTO INTEGRAL BILLETSOriginal Filed June 17, 1964 9 sheetsshee 5 9 Sheets-Sheet 4 E.SCHNECKENBURGER ET AL 3,483,915 METHOD OF FORM CONTINUOUSLY'CAST METALSTRAND INTEGRAL BILLETS Dec. 16, 196 9 Dec. 16,1969 5. SCHNEKE uaesnETAI- 3,483,915

METHOD OF FORMING CONTI USLY'CAST METAL STRAND INTO INTEGRAL BILLETS 9Sheets-Sheet 5 Original Filed June 17, 1964 1 i l I m Q Dec. 16, 1969 ESCHNECKENBURGER ETA!- 3,483,915

METHOD OF FORMING CONTINUOUSLY-CAST METAL STRAND INTO INTEGRAL BILLETS 9Sheets-Sheet 6 Original Filed June 17, 1964 it} Fiji-l7 2 f L i L l LDec. 16, 1969 E. SCHNECKENBURGER ETAL 3,483,915

METHOD OF FORMING CONTINUOUSLY'CAST METAL STRAND INTO INTEGRAL BILLETSOriginal Filed June 17, 1964 9 Sheets-Sheet 7 Fig. 12

Dec. 16, 1969 E, SCHNEKENBURGE ETAL 3,483,915

METHOD OF FOR NG CONTINUOUSLY-C METAL STRAND o INTEGRAL BILLETS 9Sheets-Sheet 8 Original Filed June 17, 1964 Dec. 16, 1969 E.SCHNECKENBURGER ETA!- 3,483,915

METHOD OF FORMING CoNTINUOUSLY-CAST METAL STRAND INTO INTEGRAL BILLETSOriginal. Filed June 17. 1964 9 Sheets-sheet 9 Fig. 75

United States Patent 3,483,915 METHOD OF FORMING CONTINUOUSLY-CAST METALSTRAND TNTQ INTEGRAL BILLE'IS lEmil Schneckenburger, Emmenbruclre,Lucerne, and

Armin Thalman, Uster, Zurich, Switzerland, assignors toAktiengesellschaft der Von Moosschen Eisenwerke, Lucerne, SwitzerlandOriginal application June 17, 1964, Ser. No. 375,775. Divided and thisapplication Jan. 25, 1968, Ser. No. 714,390 tClaims priority,application Switzerland, June 25, 1963, 7,834/ 63 Int. Cl. B22d 11/06US. Cl. 164-76 15 Claims ABSTRACT OF THE DISCLOSURE A continuously castmetal strand is formed into a plurality of integral billets by forminglongitudinal grooves in the strand which change thecross-sectional shapeand enlarge the circumference of the strand.

This is a division of application Ser. No. 375,775 filed June 17, 1964,now abandoned.

This invention relates to continuous casting, and more particularly,relates to casting of billets by casting a strand and forming of saidstrand into a plurality of integrally formed billets.

Direct casting of billets has the severe drawback that the rate ofpouring must be held at a low rate due to the relatively small crosssectional area of the individual billet. Thus, production heats cannotbe utilized directly since the molten material will cool downexcessively during the long pouring time.

Casting a plurality of billets from a single heat intro duces thecomplexity and expense of parallel molds and distribution networks forfeeding each mold with molten metal.

Casting a plurality of billets from a single mold of outlineconfiguration corresponding to the shape of interconnected billets hasbeen proposed but has encountered difiiculty in feeding such molds withwashout and mold damage.

Casting of strands and forming the strands by rolling after strandsolidification has been done but requires massive equipments, highforming pressures, and relatively large processing areas.

It is, therefore, an object of this invention to provide an improvedmethod and apparatus for casting of billets at rates compatible withdesired pouring rates of production heats.

It is a further object of this invention to provide an improved methodand apparatus for billet casting in which a slab is cast in a continuouscasting mold and in which the cast slab is formed during secondarycooling thereof into a plurality of connected billets by forming meanswhich form the slab about the molten core thereof, changing theperipheral length of the slab skin during such formation.

In accordance with these objects, there is provided, in a preferredembodiment of the present invention, a mold for casting a slab, ie. astrand of rectangular configuration. Forming means are provided to formthe cast strand into a plurality of interconnected billets duringpassage through the secondary cooling zone of the casting plant. Inaccordance with the method of this invention, the slab is formed intothe shape of interconnected billets by cnotrolled increase in theperipheral dimension of the skin of the cast slab. Preferably, theforming means comprises grooved rollers.

Patented Dec. 16, 1969 By this method, lower forming pressures areencountered and the cast structure is formed having higher density. Atthe same time, the casting rate is high enough to properly utilize themolten metal from a production heat without need for reheating.

Having briefly described the present invention, it will be described ingreater detail in the following portions of the specification, which maybest be understood by reference to the accompanying figures, of which:

FIG. 1 is a partially sectioned elevation view of a continuous castingmachine, comprising a curved mold, a curved strand guide arrangement anda separate straightcner;

FIG. 2 is a partially sectioned plan view of a continuous castingmachine similar to FIG. 1, without oscillation means;

FIG. 3 is a sectional view taken along line IIII1I of FIG. 1;

FIG. 4 is a sectioned view of a detail of FIG. 1 showing a pair ofgrooved rolls, with the adjustment device;

FIG. 5 is a cross sectional view of a slab formed to billets;

FIG. 6 is a cross sectioned view of the slab at a plurality of stationsof the machine of FIG. 1 useful in explanation of the former process;

FIG. 7 is a plot of the forming depth along the strand in the appaartusof FIG. 1;

FIG. 8 is a partially sectioned side view of a continuous casting plant,comprising a curved mold, curved and straight strand guidingarrangements and separate straightener arranged in the strand guidancepath;

FIG. 9 is a sectioned elevation view of a continuous casting machineshown schematically in part, comprising a straight mold, a straightstrand guidance means and withdrawal rolls, which follow the strandguiding;

FIG. 10 is a sectional view along line X-X of FIG. 9;

FIG. 11 is a cross sectioned view of the slab at a plurality of stationsof the machine of FIG. 9, useful in explanation of the forming process;

FIG. 12 is a schematic sectional view of a continuous casting machine,comprising a straight mold, a curved strand guide means and anindividual straightener following said strand guide means;

FIG. 13 is a sectional view taken line XIIIXIII of FIG. 12;

FIG. 14 is a schematic sectional side view of a continuous casting plantcomprising a straight mold and a curved strand guiding means;

FIG. 15 is a schematic sectional side view of a continuous castingmachine, comprising a curved mold and a curved strand guide means;

FIGS. 16 and 17 are cross sectional views of slabs formed to billets;

FIG. 18 is a side view of a dummy bar;

FIG. 19 is a sectional view taken along line XIX XIX of FIG. 18; and

FIG. 20 is a plan View of the dummy bar shown in FIG. 18.

In FIGS. 1 and 2, there is shown a continuous casting machine with acurved mold, a curved strand guiding and an individual straightener. Anopen ended water cooled mold 21 having the mold shaft curved as asection of an annulus having a middle radius R (called the castingradius) is connected inflexibly with a reciprocation lever 22, the pivotpoint 0 of which coincides with the center of the casting radius R. Themold 21 is oscillated by driving the reciprocation lever 22 by a camdisc 28. The molten metal, for example, liquid steel, is poured from aladle 24 over a tundish 25 and into the mold 21. In this mold 21, themolten steel is solidified along the cooled mold walls to form a strandor slab S with a liquid core enclosed within the formed peripheral skinand the strand is withdrawn from the mold 21 by means which will bedescribed in subsequent portions of the specification.

A curved strand guiding means 26 is positioned to receive the slabissuing from the mold 21. In the strand guiding means 26 grooved rollers27, 27a, 27b are arranged on both sides of the strand S. These groovedrollers are preferably arranged in the structure of the strand guidingmeans 26 (not shown) so that the working faces of the rollers arepositioned along two concentric circular curves 0, d, of which thedistance t is equal to the longest distance 11 between the twolongitudinal sides of the mold shaft or chamber of the mold 21 and thecenter of which coincide with the center of the casting radius R. Thesecircular curves are, therefore, identical with the inner side and theouter side of the curved strand S, and the circular curve with thecasting radius R is identical with the axis of the strand. The groovedrollers 27 in the first part of the strand guiding 26 are rotatablymounted to serve as idler rollers. The grooved rollers in the rest ofthe guide the neighboring pair or pairs of grooved rollers. The \Ygrooved rollers 27b are driven in similar manner by a motor 31 overdrive shaft 32 and a gear 33. Change of the circumferential speed of theindividual grooved rollers, required by the specific forming process,can be achieved by variation of the speed of the drive motor, the numberof gear teeth of the enmeshed gears and diameter of the rollers. Forplants having only a small number of passes, single drives for eachgrooved roller can be provided.

Between the grooved rollers 27, rotatably mounted idler rollers 34 arearranged to support the solidified skin of the strand S against theferrostatic pressure of the liquid core. Each supporting roller 34 hasthe same shape as the preceding grooved roller 27 to support thelongitudinal sides of the strand and to prevent bulging of the skin.With smaller cross sections, no supporting rollers are necessary.

At the structure of the strand guiding means 26, feed pipes 35 for thecooling water are arranged. These feed pipes are connected to spraynozzles 36 which are arranged between the grooved rollers 27a, 27b,respectively, the grooved rollers 27 and the supporting rollers 34 sothat their spraying fans are directed onto the strand S. Some of thesespraying nozzles 36 can be arranged in a way that their spraying fansare directed Onto the strand surface and the surface of the groovedrollers.

As shown in FIG. 3, the grooved rollers 27b comprise hollow spaces 37for the cooling of the grooved rollers and also for the cooling of thestrand surface. These hollow spaces 37 comprise an inlet 38 and anoutlet 39 for the cooling water.

FIG. 4 shows a sectional view of the grooved rollers 27b which can beadjusted to the desired pass depth on the til inner side of the curvedstrand by means of an adjusting device, comprising spindles 40 and theirdrive. This adjustment device can also be replaced by hydraulic means.

The smaller sides of the mold chamber of the mold 21 (FIG. 2) consist oftwo sides 41 and 41a which are arranged at an angle to each other. Thelength of these sides is equal to the length of one side of a billetformed of a strand so that by forming billets of one strand, two sides,each of the outer billets, are cast. The lateral boundaries 42 of thegrooves in this case are only for supporting and guiding of the strand.

A straightener 45 (FIGS. 1 and 2) consisting of pairs of straighteningrollers 46 follows the strand guiding means 26. Each pair ofstraightening rollers 46 comprises a driven roller 46a, and anadjustable roller 46b. In the example shown, the adjustment is achievedby hydraulic means. The rollers 46:: are driven by a motor 47 at anadjustable speed. A drive shaft 48 and a chaindrive 49 connect the motor47c to the rollers 46a. The straightening rollers 46a, 46b are formedasgrooved rollers. Between the straightening rollers 46a, 46b, spraynozzles 48 are arranged for the cooling of the strand S and thestraightening rollers 46a, 46b. The distance of the bottoms of thegrooves between the two straightening rollers of one pair ofstraightening rollers 46 is also equal to the distance i.

In the straightened part of the strand S following the straightener 45,a device 50 for longitudinal cutting is arranged. In the example shown,the cutting device comprises a cutting torch 51 for each flashing or ribconnecting the billet forms of the strand. It is also possible to use adevice with cutting rollers.

A transversal cutting device 52 known to the art for cutting the strandand/ or the billets to the desired length follows the longitudinalcutting device 50.

According to the following functional description. billets of the crosssection shown in FIG. 5 shall be formed out of a slab. In FIG. 5, theslab to be formed into billets shows three billet forms 55 which areconnected by flashes 56. The dummy bar (described in detail in asubsequent portion of the specification) which corresponds approximatelyin its cross section to the form shown in FIG. 5 and is guided in thebottom of the grooved rollers, is introduced by means of thestraightener 45 into the mold. The head of the dummy bar having a crosssection equal to the mold chamber is fixed on top of the dummy bar.

The liquid steel poured into the curved mold 1 is cooled along theperiphery to form a skin defining a curved slab in which the shortersides are already shaped in billet form. This slab is withdrawn by thedummy bar which is driven by the straightener 45. The cross section ofthe slab with a liquid core is formed in the strand guide means 26 bythe grooved rollers 27 following the mold 21 during solidification ofthe strand and accompanying an increase in the peripheral dimension ofthe strand. This circumferential extension can also be enlarged to theform according to FIG. 5 by the straightener 45. This circumferentialextension is effected by a grooved roller guiding and cooling the slab,whereby the additional cooling of the slab is achieved by the watercoming out of the spray nozzles. The ferrostatic pressure is resisted bythe grooved rollers and in the upper part of the strand guiding means 26also by the supporting rollers 34.

In FIG. 6, the form of the grooves and the variation in groove depth isshown in percent for the formation of the slab into three 'billets. Inthe example shown, the slab is formed by fifteen sequential formingsteps, each of which slightly stretches the peripheral skin of the slabuntil formed in the billet configuration. The cross section of the slabin this example has a dimension of 350 x 114 mm. and the cross sectionof the billet is 86 x 86 mm. The thickness of the flashes or ribs afterthe fifteenth pass is 10 mm.

In FIG. 7, the increase in the pass depth for the above mentionedexample is shown as a function of the pass number in form of a curve. Onthe abscissa, the pass depth is shown and of the ordinate said passnumber which reaches a maximum with fifteen passes. This curve ispreferably chosen so that the contraction from groove to grooveincreases with progressing solidification. This increase of thecontractions can also proceed in linear direction.

The deformation of the slab, originating in the grooves, is preferablyallocated mostly in the longitudinal direction of the strand. As thecross section dimension of the mold chamber of the mold 21 destinatesthe outer dimension of the billets to be formed, the alteration of theouter cross section dimension of the slab for the assumed example is notwanted. Due to the slow increase of the contractions in the strand crosssection, the deformation has mainly an effect on the feeding rate of theliquid steel until the skin contacts to separate the liquid core.

After leaving the strand guiding means 26, the solidified external zoneof the strand shows such a thickness that the main circumferentialincrease can be achieved by the rollers in the straightener 45, wherebythe strand is straightened and further cooled at the same time by watercoming out of the spray nozzles 48.

By constant contraction of the cross section of the slab, the quantityof the material in the area of the flashes or ribs is reduced and,therefore, also the amount of heat to be eliminated. If the cooling iscontinued in this area too much, cooling of the steel in the area of theflashes and, thus, an excessive increase of the roller pressure wouldoccur, especially after dividing of the liquid core by the skin. Inorder to eliminate this disadvantage, the cooling is decreased in thisarea. This may be achieved by applying insulations in the cooling hollowspace 37 of the grooved rollers in the area of the contractions and byreduction of the spray by spraying nozzles 36 and 48. A furtherpossibility of decreasing the cooling effect is to blow away the wateror to exhaust the water in the said areas.

By the rolling effect, the area of contact between the strand and thesurface of the grooved rollers is enlarged. Due to the rolling pressure,a more intensive contact of the areas is achieved so that the heattransfer is improved. Therefore, the strand may only be cooled by thegrooved rollers within the strand guiding means 26. This cooling mayalso take place only over a certain part of the strand.

Beside the straightener 45, the positively driven grooved rollers 27aand 27b also provide for the withdrawal of the strand.

When the slab has left the straightener, it shows the form according toFIG. 5, i.e. the form of the billets are connected by flashes 56. Bymeans of the cutting torches 51, the billets will be cut according tothe cutting lines 57, so that billets are achieved, which can be formedto the desired product without further working. By means of transversecutting device 52, the billets are cut to the desired length. For thefurther processing, it may be advantageous to cut longitudinally in alater step of the process.

For achieving a dense structure, it is advantageous that at least thelast pass is arranged behind the liquid core, thus, eliminating theshrinking porosity during its formation in the end area of the liquidcore. In some cases, it is advantageous to start with the formation ofthe strand only when the greater part, for example, 73 of the strandcross section is already solidified. Such an example is shown in FIG. 8.

As the elements in this example are equal to the elements of the exampleshown in FIG. 8 and numbered with the same numbers, only elements whichare unequal are numbered as follows. The strand guiding and formingmeans 26 shows instead of the grooved rollers 27 and 27a of FIG. 1,supporting rollers of known construction between which the strand iscooled by means of spraying nozzles 36. The first driven group ofrollers are the grooved rollers 27b, the second group are the groovedrollers of the straightener 45 and the third group the grooved rollers27c. In this example, a strand guiding is shown which is elongated tothe straight part of the strand, thus, enabling the application of thegrooved rollers with the greater roller pressure in the straight part,which is advantageous in respect of the costs of the construction.

FIG. 9 shows another example, in which the circumference of the strandbeing cast in a straight mold with a rectangular mold chamber isenlarged in a straight strand guiding means 66.

Elements which correspond with those of FIG. 1 are numbered equally andare not further described. The mold 65 is reciprocated by areciprocating machine 69 of known design. The design and the function ofthe strand guiding means 66 are similar to the strand guiding means 26.The grooved rollers 27, 27a, 2715 are arranged in the strand guidingmeans 66, so that the connection of the bottoms of the grooved rolls inlongitudinal strand direction on both sides of the strand forms twoparallel lines a, b, the distance t2 of which is equal to the largestdistance of the longitudinal walls of the mold 65.

The strand guiding means 66 is followed by a withdrawal device 67 ofknown design. FIG. 10 shows that the withdrawing rolls are grooved andserve for withdrawing of the strand and at the same time for thecircumferential increase of the strand. The distance between the bottomsof the grooves of a pair of withdrawal rolls is equal to the distancet2. The adjustment of the withdrawing rolls arranged on one side of thestrand S is achieved by hydraulic means 66 of known design.

According to the shape of the mold 65, a strand of rectangular crosssection is cast so that the ends must be formed during the forming tobillets. FIG. 11 shows an example of grooved rolls with fifteen passes,through which a slab of 468 x 114 mm. is formed into four billets. Thealteration of the pass depth is given in percents. The thickness of theflashes after the fifteenth pass is 10 mm.

FIG. 12 shows another example of a continuous casting machine, in whichthe circumference of the strand, cast in a straight, preliminary shapedmold 7 0 is increased in a strand guide 71 following this mold 70, inwhich strand guide the strand is simultaneously guided, cooled, curvedand straightened in a separate straightener.

Most of the elements of this example are the same as the elements in theexample according to FIG. 1. They are, therefore, equally numbered. Onlythe function of the different elements is explained as follows.

The two longitudinal sides of the mold 70 are shaped as shown in FIG.13, thus, casting a straight, profiled strand. The following grooves areshaped according to this profiled strand. The grooved rollers 27, 27a,27b are arranged in the strand guide, so that the connection of thebottoms of the grooves in longitudinal direction of the strand on theinner and outer curve is formed by two nearly parallel curves k1, k2shaped by different sections b1, b2, b3 of different radii r1, r2, r3.The distance t3 of the curves k1, k2 is equal to the longest distance :4between the two longitudinal sides of the mold chamber of the mold 70.By this arrangement, the strand in the strand guiding means 51 is bentslowly into the horizontal line according to the said curves. Withmachines positioned below floor level, the bending may be more than sothat the strand can be transported to the floor on a table rollerwithout further means.

Following the strand guiding 71, a separate straightener 45 forstraightening and further forming of the strand is arranged, as shown inFIG. 1 following the straightener 45, a transverse cutting device 52 isarranged, which separates the formed strand into sections of the desiredlength. The longitudinal cutting and completion to billets is effectedin a separate process outside of the continuous casting machine.

In FIG. 14, there is shown a continuous casting machine in which thecircumference of a strand cast in a straight mold 75 is increased in acurved strand guiding means 76 following this mold, for guiding,additional cooling bending and straightening the strand.

In respect to the already described figures, only the differingpositions are mentioned. All grooved rollers are driven in groups. Thestrand guide means 76 consists of two main parts. The first part extendsfrom the mold 75 to point P. In this part, the radii of the curvesdecrease to the point P so that the strand is exposed to an increasingbending. The second part reaches from point P to the horizontal line. Inthis part, the radii of the curves increase until passing over to thehorizontal line so that the strand is exposed to an increasingstretching. The withdrawing of the strand S from the mold 75 is achievedby the positively driven grooved rollers 27a. Following the strand guidemeans 76, the strand S is to billets 7 cut by a saw 77 into billets. Thebillets can then be cut by following shears.

FIG. shows a further continuous casting machine in which thecircumference of a strand cast in a curved mold 80 is increased in acurved strand guide following the mold in which strand guide the strandis guided, cooled and straightened.

In this example, only the differing parts are explained. The strand castin a curve with a casting radius R1 is guided by supporting rollers in apart of the strand guide, extending from the mold to a point P1, andcooled by water coming out of the spraying nozzles 36. Starting withpoint P1, the radii of each of the segments increase in relation to theradius R1, so that the strand S is exposed to an advancing stretchinguntil it is straightened. The withdrawing of the strand is achieved bypositively driven grooved rollers 27b.

According to FIG. 5, the contractions of the grooves are arranged sothat the billet forms are situated edge-toedge and that they areconnected by the flashes 56. In order to increase the amount of materialin the area of the flashes 56 and, thus, to maintain a highertemperature in these flashes, according to FIGS. 16 and 17, the edges 35are formed by grooved rollers for increasing the circumference of aslab, so that over a portion M of each neighboring side 86, 87, jointbillets 88, 89 and are achieved. The portion M represents the size ofthe flash (FIG. 5) with the same depth of groove. By transposing thecontractions in the groove of grooved rollers placed opposite eachother, the apexes of the contractions are transposed, resulting in hightemperature in the flashes and lower rolling pressures. A furtheradvantage of transposing the contractions and overlapping of neighboringsides 88, 87 is that the efliciency of the cross section of the slaband, thus, the output of the machine is improved.

The difference between the FIGS. 16 and 17 is that in FIG. 17 the sides88, 87 of neighboring billet forms 88, 89 and 89, 90 respectively, arearranged in cutting distance n, whereby in FIG. 16 they are aligned.

By the above mentioned cutting devices 61 or hot saws 77, the billetsare divided and the sides 86 and 87 in their part M are formed intobillets.

On starting the casting, the mold is closed in its lower part by meansof a dummy bar head, connected to a dummy bar. This dummy bar is placedonto the mold by means of the withdrawal rollers. As soon as the steelfed to the mold is solidified at the dummy bar head, the strand bingformed is withdrawn from the dummy bar by means of the withdrawalrollers. The dummy bar according to the invention is shown in FIGS. 18to 20 for a plant with curved strand guiding means. As shown in FIG. 20,a dummy bar 92 comprises a dummy bar head 93 for a mold without apre-shaped mold chamber. The dummy bar 92 is flexible and, for example,may be made of rubber. The bar has a cross section according to thefinal form of the strand cross section as shown in FIG. 5, so that itcan be passed through the groove of the strand guiding means. As thebottoms of the grooves of all rolls have the same distance from themiddle of the strand, the dummy bar 92, which is transported by thestraightener and/ or the positively driven grooved rolls, is guided bythese bottoms of the grooves or its apexes 94. These apexes 94 areslightly larger than the bottoms of the grooves, so that in the bottomof the groove a Wide and maximum possible surface is achieved.

The centers of the shaped single cross sections are provided with asteel core 95. Each steel core 95 is connected to a coupling piece 96.This coupling piece 96 and the following part of the steel core 95 areseparated from the dummy bar 92 by asbestos for heat insulation.

The dummy bar head 93 consists of several super-positioned plates 97, aninsulation layer 96 for screening the heat against the dummy bar 92 andbolts 99. These bolts 99 are connected by means of connecting bolts 100to the coupling piece 96. The number of plates is chosen in a way thatthey cannot be completely melted by the liquid steel, but that theremaining plates have a temperature high enough for being formed by thefollowing grooved rollers. The steel cores 95, the coupling pieces 96and the connection bolts 100 and the bolts 99, surrounded by thesolidified steel, transmit the withdrawal force to the strand bengformed.

The shape of the cross section of the dummy bar may be the same as thecross section of the mold chamber. The grooved rollers have to bearranged movably by bydraulic means, so that-they can be put aside forintroducing the dummy bar. In this case, the grooved rollers will be putinto position when the beginning of the strand has passed.

For these examples, a great number of passes have been chosen. Thisnumber can be reduced considerably in many cases.

This invention may be variously modified and embodied Within the scopeof the subjoined claims.

What is claimed is:

1. The method of continuous production of profiled strands, whichcomprises the steps of continuously casting a strand having a crosssection of different shape than desired for the finished strand and asolidified periphery enclosing a molten core, withdrawing said strandfrom said mold, cooling the strand to further solidify it, and hotforming said strand during the latter cooling to change the shape, andto enlarge the circumference, of the cross section of the strand.

2. The method according to claim 1 in which the cast strand is a slabhaving an approximately rectangular cross section and the desired shapeof said finished trands comprises a cross section of a plurality ofbillets being connected side by side to each other.

3. The method according to claim 1 in which said strand is hot formed byforming rollers.

4. The methd in accordance with claim 1, in which the deformation of thestrand during hot forming is controlled to increase longitudinally ofthe strand.

5. The method in accordance with claim 4, in which the feeding rate ofmolten metal is controlled in accordance with the deformation.

6. The method in accordance with claim 1, in which the main hot formingis done when the bigger area of the cross section of the cast strand hasalready solidified.

7. The method in accordance with claim 1, in which a bent strand isguided and straightened, hot forming said strand during straightening.

8. The method in accordance with claim 1, in which a bent strand isguided and straightened, beginning the hot forming when the strand isstill bent and continuing said hot forming when the strand has beenstraightened.

9. The method according to claim 2, in which said slab is symmetricallyhot formed by grooving the two longer sides of the slab so that theformed billets are positioned in a corner-to-corner disposition.

10. The method according to claim 2, in which said slab is formed bygrooving the opposed long faces thereof, the grooves on one face beingoffset from the grooves on the other face so that billets are hotformed, said billets being connected by overlapping neighboring sidefaces.

11. The method according to claim It in which overlapping neighboringside faces are hot formed in one plane.

12. The method according to claim 10, in which the overlappingneighboring side faces are hot formed each in a plane and that theseplanes are parallel to each other, being connected by a landsubstantially equal to the cutting width of the separating device usedfor separation of the billets.

13. The method according to claim 2, in which the strand is cast as aslab, the smaller side faces of which are formed according to twobillets side faces including the respective angle between each other.

9 10 14. The method according to claim 2, in which the 3,147,521 9/1964Boehm 16470 strand is cast having a cross section profiled according to3,209,452 10/1965 Schneckenburger 164-283 X the followin rooves.

15. The ?n ethod according to claim 2, in which a FOREIGN PATENTSplurality of passes are provided for hot forming and the 1,313,423 962Ffancfiamount of reduction is enlarged non-linear from pass 0 173,33211/1960 sw fin.

to pass.

J. SPENCER OVERHOLSER, Primary Examiner R. SPENCER ANNEAR, AssistantExaminer References Cited UNITED STATES PATENTS 10 494,659 4/1893 Very164-483 X US. Cl. X.R. 2,008,626 7/1935 Murakarni. 7 2,698,467 1/1955Tarquineeetal. 164283X 29 528164

